Refrigerator including combination evaporator fan motor and defrost control



Dec. 8, 1964 D. A. SOLLEY, JR 3,159,930

REFRIGERATOR INCLUDING COMBINATION EVAPORATOR FAN MOTOR AND DEFROSTCONTROL Filed July 17, 1963 SUPPLY LINES INVENTOR.

DOUGLAS A SOLLEY. TR.

515% 2 H\ ATT RNEY F'IG.3

United States Patent 3,159,930 REFRIGERATOR INCLUDING CGMBINATIGNEVAPGRATGR FAN MOTOR AND DEFRGST CON'lROL Dougm A. Solley, Era, FernCreek, Ky, assignor to General Electric Company, a corporation of NewYork Fiied Italy 17, 1963, Ser. No. 2%,e61 3 Qlaims. (Cl. 62155) Thepresent invention relates to refrigerators of the type in which at leastone compartment is maintained at the desired refrigerating temperaturesby means of an air stream circulated over an evaporator positionedoutside of or separate from the compartment and is particularlyconcerned with a refrigerator of this type including a combination fanand defrost control including a single drive motor.

Various refrigerators are known in which the storage compartment hasbeen maintained at the desired refrigerating temperature by the forcedcirculation of air over an evaporator disposed outside of thecompartment and through the compartment. By positioning the evaporatorotuside the compartment, it may be periodically warmed to defrostingtemperatures Without substantially afiecting the storage temperatureswithin the compartment. During the defrost operation of the evaporator,the fan for circulating air is de-energized and the present invention isparticularly concerned with a forced air cooled refrigerator in whichthe fan motor also provides means for operating the defrost controlmeans.

A primary object of the invention is to provide a forced air cooledrefrigerator including a storage compartment, an evaporator positionedoutside of the compartment, a fan for circulating air from thecompartment over the evaporator and a defrost control means operated bythe fan motor for controlling the periodic defrosting of the evaporator.

Another object of the invention is to provide a forced air cooledrefrigerator including an evaporator disposed outside of therefrigerator storage compartment, a motor driven fan for circulating airover the evaporator and through the compartment and defrost controlmeans dis posed in the relatively dry portion of the circulating airstream downstreamfrorn the evaporator. 1

Further objects and advantages of the invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaims annexed to and forming part of this specification.

In accordance with one embodiment of the present invention, there isprovided a refrigerator including a storage compartment, an evaporatordisposed outside of that compartment and a duct defining an air flowpassageway outside of the compartment for the circulation of air fromthe compartment over the evaporator. A fan is provided at the outlet endof the duct and means are provided for energizing the motor driving thefan only when refrigerant is being supplied to the evaporator. A defrostcontrol means for initiating periodic warming of the evaporator todefrosting temperatures is driven by the fan motor so that theevaporator is periodically defrosted as a function of the fan motorrunning time. In the preferred embodiment of the invention, thecombination fan, fan motor and defrost control means is disposed in thepath of the air flowing from the evaporator to the storage compartmentwhich air is relatively free from moisture.

For a better understanding of the invention reference may be had to theaccompanying drawing in which:

FIGURE 1 is a side elevational view of a refrigerator cabinet embodyingthe present invention;

FIGURE 2 is an enlarged sectional view of a portion of the cabinetillustrated in FIGURE 1;

FIGURE 3 is a schematic illustration of a refrigerating system employedfor refrigerating the cabinet of FIG- URE 1; and

FIGURE 4 is a sectional view taken generally along line 44 of FIGURE 2.v

While the invention is applicable to refrigerators containing one ormore storage compartments, it will be described with specific referenceto a refrigerator comprising a single storage compartment cooled by theforced circulation of air over an evaporator disposed outside of thatcompartment.

With reference to FIGURE 1 of the drawing, there is shown an embodimentof the present invention in the form of a household refrigeratorincluding a storage compartment 1 defined by a plurality of insulatedwalls including a rear wall 2, the access opening to the compartmentbeing closed by a door 3. The compartment 1 is maintained at desiredrefrigerating temperatures by means of a single evaporator 4 positionedin the insulated rear wall 2 of the cabinet. Condensed refrigerant issupplied to the evaporator 4 from a condensing unit positioned in thelower portion of the cabinet and including a compressor 5 and acondenser 6.

More specifically the evaporator 4 is disposed in an enlarged portion ofa duct '7 having an inlet opening 8 communicating with the lower portionof the storage compartment 1 and an outlet 9 at the upper end of theduct. A fan 1% driven by a motor 11 is disposed in the outlet end of theduct 7 and is designed to draw air upwardly through the duct 7 over theevaporator 4 to discharge the cooled air into the storage compartment 1.

A suitable automatic defrost refrigerating system is shown schematicallyin FIGURE 3 of the drawing. In addition to the evaporator 4, thecompressor 5 and the condenser 6, the system includes a capillary flowrestrictor 12 connecting the outlet end of the condenser 6 to theevaporator 4, these components being connected in series flowrelationship so that the evaporator 5 withdraws vaporized refrigerantfrom the evaporator 4 through a suction line 13 and discharges highpressure refrigerant to the condenser 6 through the discharge line 14.For the purpose of periodically warming the evaporator 4 to defrostingtemperatures there is provided a bypass or defrost line 15 connectingthe compressor discharge line 14- to the inlet end of the evaporator 4.A normally closed defrost valve 17 provided in the line 15 andcontrolled by means or" a solenoid 18 is periodically opened so that hotcompressed refrigerant vapor is bypassed to the evaporator through thedefrost line 15 for warming the evaporator to defrosting temperatures.The valve 17 is of a construction such that whenthe bypass line 15 isopen, the valve 17 also introduces a restriction into the suction line13 controlling the flow of condensed refrigerant from the defrostingevaporator 4 back to the compressor 6.

The operation of the compressor 5 and the fan motor 11 is controlled bya control circuitry including a cold control thermostat 21 having itssensing bulb 22 positioned Within the storage compartment 1 for sensingthe temperatures within that compartment. The thermostat 21 is adaptedto energize both the compressor 5 and the fan motor 11 whenever thetemperature within the compartment 1 is below a predetermined minimumand to de-energize the compressor and the fan motor when the compartmenttemperature reaches a predetermined maximum. As is shown in FIGURE 2,the compressor 5 and the fan motor 11 are connected in parallel so thatthe fan operates only when the compressor 5 is also energized duringnormal refrigerating operation of the refrigerating system.

:J In accordance with the present invention, the control circuitry alsoincludes defrost control means for operating tained within a housing 24which along with the fan motor 11 is disposed in the upper end of the.duct 5. The switch 23 includes a magnetic switch arm 25 movable intoengagement with either a fan motor energizing contact 26 or a defrostvalve energizing contact 27. As is shown in FIGURE 4 of the drawing, amagnetfid provided within the housing 24 is provided for operating theswitch arm 25 from one contact to the other. More specifically, theswitch 23 is of the type in which the arm 25 is spring biased intoengagement with the contact 27 when the switch is not subjected to thefield of the magnet 28 but is designed to be magnetically transferredinto engagement with the contact 26 when the magnet 28 is brought intoclose proximity with the non-magnetic switch envelope 30.

The purpose of the switch 23 is to energize the fan motor 11 wheneverthe compressor is running under normal refrigerating operation of therefrigerator and to energize the defrost valve 17 with the compressorrunning during defrost operation of the refrigerator. In order toperiodically initiate a defrost cycle and also time the length of thatcycle, means are provided for moving the magnet 28 out of operatingposition relative to the switch 23 after a given period of operation ofthe fan motor 11 and for again establishing magnetic contact between themagnet 28 and the switch 23 after a predetermined time sufficient toinsure the removal of all of the frost from the defrosting evaporator 4.

The structure of the defrost control means designed to accomplish theseresults is shown in FIGURE 4 of the drawing. With reference to thatfigure, it will be seen that the switch 23 is secured by means of an arm32 to one end of a bellows 35 forming part of a double bellows structureincluding a bellows 36. The two bellows 35 and 36 are filled with aliquid and are connected by means of a timing orifice or aperture 37.The liquid fill for the bellows may be a silicone oil, an alcohol or asimilar liquid which has a freezing point lowerthan any anticipatedoperating condition of the control. The bellows 36 is biased to aretracted or compressed position by means of a spring 39, thecompressive force of which can be ad justed by means of an adjustingscrewed. When the spring compresses the bellows 36, the fluid containedwithin the double bellows structure is displaced into the bellows 35 sothat this bellows is in turn extended.

The magnet 28 is carried on the free end of a pivoted lever arm 41 andthis arm is normally biased into magnetic engagcrnentwith the switch 23and mechanical engagement with the foot or pad 42 at the end of thebellows 35 by means of a cam 43. The cam 43 in turn is connected to thefan motor Ill through a suitable gear train (not shown) so that, forexample, the cam 43 will rotate one revolution during normal operationof the fan motor 11 during a 12 hour period.

The cam 43 includes a shoulder 45 which is designed to function as atiming means and initiate a defrost cycle after one complete revolutionthereof. More specifically, during normal operation of the defrostcontrol means, rotation of the cam 43 normally maintains the magnet 28in operating position relative to the switch 23 and also maintains thearm 41 in engagement with the pad 42 provided on the bellows 35. c Asthe cam rotates in a counterclockwise direction as viewed in FIGURE 4,thearm 41 is gradually moved to the right thereby slowly'compressing thebellows 35 while at the same time maintaining the magnet 28 in operativeposition relative to the switch 23 supported on the bellows 35 so thatthe fan motor is energized through that switch. After apredeterminedperiod 4 of time, the cam rotates to the point such thatthe arm 41 trips off of the shoulder 45' under the action of the biasingspring 46. This results in the magnet 28 being removed from operatingproximity to the switch 23 whereby the switch arm 25 becomes disengagedfrom the contact 26 and engages the contact 27 thereby energizing thedefrost valve 17. At the same time, the switch arm 41 becomes disengagedfrom the pad or foot 42 removing the compressive forces thereof from thebellows 35. As the bellows 35 slowly expands by the return of fiuidthereto through the aperture 37 due to the retoring spring forces ofeach bellows and the force of the spring 39 on the bellows 36, theswitch 23 carried by the bellows 35 moves to the left until it is againpositioned adjacent to the magnet 28. At this point, the switch 23 isreturned to its r normal position in which the switch arm 25 is inengagement with the contact 26 thereby terminating the defrost cycle andagain placing the operation of the fan motor 11 under the control of thethermostat 21. A new refrigerating cycle is thus initiated and the fanIt) and compressor 5 will cycle on and off to maintain the desiredtemperatures within the compartment 1. Also when contact of the switcharm 25 with the contact 27 is broken, the solenoid valve 17 isde-energized so that flow of the defrost gas through the line 15 isstopped and normal refrigerant flow through the condenser 6 to theevaporator is reestablished. 7 V

The size of the orifice or opening 37 of course determines the length ofthe defrost cycle using any given bellows charging liquid. The exactsize will depend upon the viscosity of the liquid fill for the bellows35 and 36 under the operating conditions of the defrost control meansand the amount of heat which can be supplied to the evaporator '4 duringthe defrost cycle. It will be understood, of course, that while a hotgas has been illustrated as means for warming the evaporator 4 todefrost temperatures, other suitable means such as electric heat mayalso be employed in which case the control of the heating means will bethe same as that used in the control of the defrost valve 17 but thecompressor 5 is also placed under this control so thatthe refrigeratingefiect resulting from the operation of the compressor during the defrostcycle will not oppose the defrost action of the electric or resistanceheating. However, in the preferred embodi merit of the. invention, hotgas is employed for defrosting the evaporator 4 and thecompressor 5 isoperated during the defrost cycle.

It will also be apparent from the foregoing that other types of switcheswith suitable'mechanisms for operating them may be used instead of thehydraulic escapement and reed switch 23. For example, a mechanicalescapement such as is used in clock mechanisms may be used. However, thedisclosed means including a reed switch which is completely sealedwithin the glass or similar envelope 30 is preferred because of itssimplicity and high reliability under the operating conditionsprevailing in a refrigerator.

While there has been shown and described a particular embodiment of theinvention it will be understood that the invention is not limitedthereto and it is intended by the appended claims to cover all suchchanges and modifications as come within the true spirit and scope ofthe invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A refrigeratoncomprising a storage compartment, an evaporatordisposed outside of said compartment, condensing means including acompressor for normally supplying condensed refrigerant to saidevaporator, defrost means for periodically defrosting said evaporator, afan for circulating air from said compartment over said evaporator, amotor for driving said fan, a motor circuit for energizing said motoronly when said compressor is energized to supply condensed refrigerantto said evaporator, and defrost control means including timing meansdriven by said motor for initiating operation of said defrost means. 7

2. A refrigerator comprising a storage compartment, an evaporatordisposed outside of said compartment, defrost means for periodicallywarming said evaporator to defrost temperatures, condensing meansincluding a compressor for normally supplying condensed refrigerant tosaid evaporator, a fan for circulating air from said compartment oversaid evaporator, a motor for driving said fan, a motor circuit forenergizing said motor only when said compressor is energized to supplycondensed refrigerant to said evaporator, and defrost control meansincluding timing means driven by said motor for initiating operation ofsaid defrost means, said motor and said defrost control means beingdisposed in the path of the air flowing from said evaporator to saidcompartment.

3. A refrigerator comprising insulated walls defining a storagecompartment, a duct in one of said walls having the inlet and outletends thereof communicating with said compartment, an evaporator disposedin said duct, condensing means including a compressor for normallysupplyingcondensed refrigerant to said evaporator, de frost means forperiodically defrosting said evaporator, a fan in the outlet end of saidduct for circulating air cooled by said evaporator through saidcompartment, a motor for driving said fan, a motor circuit forenergizing said motor only when said compressor is energized to supplycondensed refrigerant to said evaporator, defrost control meansincluding timing means driven by said motor for initiating operation ofsaid defrost means, 'said motor and defrost control means being disposedin said duct adjacent the outlet end thereof.

Mann Oct. 6, 1959 Jacobs Nov. 28, 1961

1. A REFRIGERATOR COMPRISING A STORAGE COMPARTMENT, AN EVAPORATORDISPOSED OUTSIDE OF SAID COMPARTMENT, CONDENSING MEANS INCLUDING ACOMPRESSOR FOR NORMALLY SUPPLYING CONDENSED REFRIGERANT TO SAIDEVAPORATOR, DEFROST MEANS FOR PERIODICALLY DEFROSTING SAID EVAPORATOR, AFAN FOR CIRCULATING AIR FROM SAID COMPARTMENT OVER SAID EVAPORATOR, AMOTOR FOR DRIVING SAID FAN, A MOTOR CIRCUIT FOR ENERGIZING SAID MOTORONLY WHEN SAID COMPRESSOR IS ENERGIZED TO SUPPLY CONDENSED REFRIGERANTTO SAID EVAPORATOR, AND DEFROST CONTROL MEANS INCLUDING TIMING MEANSDRIVEN BY SAID MOTOR FOR INITIATING OPERATION OF SAID DEFROST MEANS.